Reversion in Hamster Cells Transformed by Rous Sarcoma Virus.

Hamster cells of the BHK-21 line are transformable by Rous sarcoma virus (Schmidt-Ruppin strain). The transformed cells form colonies in agar suspension culture, grow on glass in disarray, and initiate tumors in hamsters and chickens, but extracts do not induce tumors in chickens. Chickens bearing tumors develop neutralizing antibody against the virus. Transformed cell clones give rise to "revertants" which form colonies on glass with cells oriented parallel to each other like the original uninfected cells. These revertants do not grow in agar or initiate chicken tumors, and they regain the original low transplantability of untransformed cells in hamsters.